21180239 has 2 divisors, whose sum is σ = 21180240. Its totient is φ = 21180238.

The previous prime is 21180227. The next prime is 21180281. The reversal of 21180239 is 93208112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21180239 - 2¹² = 21176143 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21180139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10590119 + 10590120.

It is an arithmetic number, because the mean of its divisors is an integer number (10590120).

Almost surely, 2^21180239 is an apocalyptic number.

21180239 is a deficient number, since it is larger than the sum of its proper divisors (1).

21180239 is an equidigital number, since it uses as much as digits as its factorization.

21180239 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 21180239 is about 4602.1993655208. The cubic root of 21180239 is about 276.6794808665.

The spelling of 21180239 in words is "twenty-one million, one hundred eighty thousand, two hundred thirty-nine".